Magnesium dichloride-alcohol adducts

ABSTRACT

The present invention relates to MgCl 2 .mROH.nH 2 O adducts, where R is a C 1 -C 10  alkyl, 2≦m≦4.2, 0≦n≦0.7, characterized by an X-ray diffraction spectrum in which, in the range of 2θ diffraction angles between 5° and 15°, the three main diffraction lines are present at diffraction angles 2θ of 8.8±0.2°, 9.4±0.2° and 9.8±0.2°, the most intense diffraction lines being the one at 2θ=8.8±0.2°, the intensity of the other two diffraction lines being at least 0.2 times the intensity of the most intense diffraction line. 
     Catalyst components obtained from the adducts of the present invention are capable to give catalysts for the polymerization of olefins characterized by enhanced activity and stereospecificity with respect to the catalysts prepared from the adducts of the prior art.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of Ser. No. 09/626,712, filed Jul. 26,2000, now U.S. Pat. No. 6,323,152 which is a division of Ser. No.09/050,612, filed Mar. 30, 1998, now U.S. Pat. No. 6,127,304.

The present invention relates to magnesium dichloride/alcohol adductswhich are characterized by particular chemical and physical properties.The adducts of the present invention are particularly useful asprecursors of catalyst components for the polymerization of olefins.

MgCl₂.alcohol adducts and their use in the preparation of catalystcomponents for the polymerization of olefins are well known in the art.

J. C. J. Bart and W. Roovers [Journal of Material Science, 30 (1995),2809-2820] describe the preparation of a number of MgCl₂.nEtOH adducts,with n ranging from 1.4 to 6, and their characterization by means ofX-ray powder diffraction. A range of allegedly new adducts, with n=6,4.5, 4, 3.33, 2.5, 1.67, 1.50 and 1.25, is characterized in terms ofX-ray diffraction pattern. According to the authors, the MgCl₂.alcoholadducts can be converted to active polymerization catalyst supportsthrough the elimination of the alcohol molecules from the adducts bythermal desolvation. In table III of the article, the characteristicdiffraction lines of the above indicated new adducts are reported withreference to the interplanar distances. For convenience, the samediffraction lines are reported below with reference to the 2θdiffraction angles, limited to the range of 2θ diffraction anglesbetween 5° and 15° (the relative intensity I/I_(o) with respect to themost intense diffraction line is reported in parentheses). For n=1.25:2θ=7.6° (100), 12.28° (25), 14.9° (8); for n=1.5: 2θ=8.44 (100), 11.95(48), 14.2 (46); for n=1.67: 2θ=6.1° (9), 6.68° (100), 8.95° (50), 9.88°(33), 11.8° (8), 12.28° (33), 14.5° (13), 14.75° (4); for n=2.5: 2θ=6.3(27), 9.4° (100), 9.93° (70), 11.7° (11), 12.35° (6), 14.90 (6); forn=3.33: 2θ=9.14° (15), 9.44° (100), 11.88° (15), 12.9° (27); for n=4:2θ=8.7° (49), 10.1° (73), 10.49° (100), 11.8° (58); for n=4.5: 2θ=9.65°(100), 11.4° (10), 12.5° (24), 12.94° (32), 14.25° (20), 14.95° (6); forn=6: 2θ=8.94° (100), 13.13° (3). A MgCl₂.2EtOH.0.5H₂O adduct is alsoreported, the diffraction lines of which in the relevant range are thefollowing: 2θ=7.9° (35); 8.5° (>100); 9.7° (26); 11.32° (100); 12.59°(11); 13.46° (12).

Catalyst components for the polymerization of olefins, obtained byreacting MgCl₂.nEtOH adducts with halogenated transition metalcompounds, are described in U.S. Pat. No. 4,399,054. The adducts areprepared by emulsifying the molten adduct in an immiscible dispersingmedium and quenching the emulsion in a cooling fluid to collect theadduct in the form of spherical particles. No X-ray characteristics ofthe adducts are reported.

U.S. Pat. No. 4,421,674 describes a method for preparing a catalystcomponent for the polymerization of olefins which involves thepreparation of MgCl₂.EtOH adducts by means of the following steps: (a)preparation of a MgCl₂ solution in ethanol; (b) spray-drying saidsolution to collect particles of the adduct in spherical form, saidadduct having from 1.5 to 20% by weight of residual alcoholic hydroxylcontent and being characterized by an X-ray spectrum in which themaximum peak at 2.56 Å (i.e. 2θ=35°) characteristic of the crystallineanhydrous MgCl₂ is practically absent and a new maximum peak at about10.8 Å (i.e. 2θ=8.15°) is present; lesser peaks at about 9.16 Å (i.e.2θ=9.65°) and 6.73 Å (i.e. 2θ=13.15°) are also reported.

EP-A-700936 describes a process for producing a solid catalyst componentfor the polymerization of olefins which comprises the preparation ofMgCl₂.EtOH adducts by means of the following steps: (A) preparation of amixture having formula MgCl₂.mROH, wherein R is an alkyl group with 1 to10 carbon atoms and m=3.0 to 6.0; (B) spray-cooling said mixture toobtain a solid adduct having the same composition as of the startingmixture; (C) partly removing the alcohol from the above-obtained solidadduct to obtain an adduct containing from 0.4 to 2.8 mol of alcohol permol of MgCl₂. The adduct obtained in (C) is characterized by an X-raydiffraction spectrum in which a novel peak does not occur at diffractionangles 2θ=7 to 8° as compared with the diffraction spectrum of theadduct obtained in (B), or even if it occurs, the intensity of the novelpeak is 2.0 times or less the intensity of the highest peak present atthe diffraction angles 2θ=8.5 to 9° of the diffraction spectrum of theadduct obtained in (C). FIG. 2 of said European Patent Application showsa typical X-ray diffraction spectrum of the adducts prepared in (B). Thehighest peak occurs at 2θ=8.8°; two less intense peaks occur at 2θ=9.5to 10° and 2θ=13°, respectively. FIG. 3 shows a typical X-raydiffraction spectrum of the adducts prepared in (C). The highest peakoccurs at 2θ=8.8°; other peaks occur at 2θ=6.0 to 6.5°, 2θ=9.5 to 10°and 2θ=11 to 11.5°. FIG. 4 shows a typical X-ray diffraction spectrum ofcomparative adducts prepared in (C) The highest peak occurs at 2θ=7.6°;other peaks occur at 2θ=8.8°, 2θ=9.5 to 10°, 2θ=11 to 11.5° and 2θ=12 to12.5°.

A new MgCl₂.alcohol adduct has now been found which is characterized bya particular X-ray diffraction spectrum, not shown by the adducts of theprior art, and/or by a particular crystallinity as shown by theDifferential Scanning Calorimetry (DSC) profile of the adduct. Inaddition, particular MgCl₂.alcohol adducts of the present invention canbe characterized by their viscosity values in the molten state which,for a given alcohol content, are higher than the viscosity values of thecorresponding adducts of the prior art. In addition to the alcohol,minor amounts of water can also be present in the adducts according tothe invention.

The adducts of the present invention can be used to prepare catalystcomponents for the polymerization of olefins by reaction with transitionmetal compounds. Catalyst components obtained from the adducts of thepresent invention are capable of giving catalysts for the polymerizationof olefins characterized by enhanced activity and stereospecificity withrespect to the catalysts prepared from the adducts of the prior art.Also, the morphological properties of the obtained polymers areimproved, particularly when adducts in spherical forms are used.

The present invention therefore relates to MgCl₂.mROH.nH₂O adducts,where R is a C₁-C₁₀ alkyl, 2≦m≦4.2, 0≦n≦0.7, characterized by an X-raydiffraction spectrum in which, in the range of 2θ diffraction anglesbetween 5° and 15°, the three main diffraction lines are present atdiffraction angles 2θ of 8.8±0.20, 9.4±0.20 and 9.8±0.20, the mostintense diffraction line being the one at 2θ=8.8±0.2°, the intensity ofthe other two diffraction lines being at least 0.2 times the intensityof the most intense diffraction line.

The above described diffraction pattern is unique and it has never beendescribed in the prior art. In fact, none of the spectra reported inBart et al. corresponds to the spectrum which characterizes the adductsof the present invention; the same applies to the adducts disclosed inEP-A-700936. As for the adducts described in U.S. Pat. No. 4,399,054,applicants repeated the preparation of the adducts according to theprocedure described therein. The X-ray diffraction spectrum of theobtained adduct shows, in the range of 2θ diffraction angles between 5and 15°, the following main peaks (the relative intensity I/I_(o) withrespect to the most intense diffraction line is in parentheses):2θ=8.84° (79); 2θ=9.2 (100); 2θ=9.43 (68); 2θ=9.82 (19). Contrary to theadducts of the present invention, which are characterized, inter alia,by a most intense diffraction line occurring at 2θ=8.8±0.2°, the adductsof U.S. Pat. No. 4,399,054 are characterized by a most intensediffraction line at 2θ=9.2°.

Preferably R is a C₁-C₄ alkyl, more preferably ethyl, m is between 2.2and 3.8, more preferably between 2.5 and 3.5, n is between 0.01 and 0.6,more preferably between 0.001 and 0.4. The X-ray diffraction spectra aredetermined with reference to the main diffraction lines of silicon, usedas an internal standard, using the apparatus and the methodologydescribed hereinafter.

The preferred adducts of the present invention are characterized by anX-ray diffraction spectrum in which the intensity of the diffractionlines at 2θ=9.4°±0.2° and 9.8°±0.2° is at least 0.4 times, preferably atleast 0.5 times the intensity of the most intense diffraction line at2θ=8.8°±0.2°.

As an alternative, or in addition to the X-ray spectrum, the adducts ofthe present invention are characterized by a Differential ScanningCalorimetry (DSC) profile in which no peaks are present at temperaturesbelow 90° C. or, even if peaks are present below said temperature, thefusion enthalpy associated with said peaks is less than 30% of the totalfusion enthalpy.

The DSC analysis is carried out using the apparatus and the methodologydescribed hereinafter.

When R is ethyl, m is between 2.5 and 3.5 and n is between 0 and 0.4,the fusion enthalpy associated with peaks possibly present attemperatures below 90° C. is less than 10% of the total fusion enthalpy.In said case the adducts are furthermore characterized by the fact thatthe maximum peak occurs at temperatures between 95 and 115° C.

Particularly preferred are adducts of the formula (I)

MgCl₂ .mEtOH.nH₂O  (I)

where m is between 2.2 and 3.8 and n is between 0.01 and 0.6, havingboth the above described X-ray spectrum and the above described DSCfeatures. Adducts of this type can be further characterized by theirviscosity in the molten state. In fact, it has been unexpectedly foundthat adducts with the above described features are also characterized byvalues of viscosity which, for a given alcohol content, are higher thanthe values of viscosity of the corresponding adducts of the prior art.In particular, on a plot of viscosity vs. EtOH molar content, the valuesof viscosity at 115° C. (expressed in poise) of the adducts (I) areabove the straight line passing through the points having, respectively,a viscosity/EtOH molar content of 2.43/2.38 and 1.26/3.31; at 120° thevalues of viscosity of the adducts (I) are above the straight linedefined by the points having viscosity/EtOH molar content values of1.71/2.38 and 0.9/3.31; at 125° the values of viscosity of the adducts(I) are above the straight line passing through the points defined bythe viscosity/EtOH molar content values of 1.2/2.38 and 0.63/3.31.

The adducts of the present invention can be prepared with new methods,not disclosed in the prior art, which are characterized by particularmodalities of reaction between MgCl₂, alcohol, and optionally water.

According to one of these methods MgCl₂.pROH.qH₂O adducts, where R is aC₁-C₁₀ alkyl, 1≦p≦6, 0≦q≦1, are prepared by dispersing the particles ofmagnesium dichloride in an inert liquid immiscible with and chemicallyinert to the molten adduct, heating the system at temperature equal toor higher than the melting temperature of MgCl₂.alcohol adduct and thenadding the desired amount of alcohol in vapour phase. The temperature iskept at values such that the adduct is completely melted.

The molten adduct is then emulsified in a liquid medium which isimmiscible with and chemically inert to it and then quenched bycontacting the adduct with an inert cooling liquid, thereby obtainingthe solidification of the adduct.

The liquid in which the MgCl₂ is dispersed can be any liquid immisciblewith and chemically inert to the molten adduct. For example, aliphatic,aromatic or cycloaliphatic hydrocarbons can be used as well as siliconeoils. Aliphatic hydrocarbons such as vaseline oil are particularlypreferred. After the MgCl₂ particles are dispersed in the inert liquid,the mixture is heated at temperatures preferably higher than 125° C. andmore preferably at temperatures higher than 150° C. Conveniently, thevaporized alcohol is added at a temperature equal to or lower than thetemperature of the mixture. Particularly preferred products obtainablewith the above specified method are the adducts of formulaMgCl₂.mROH.nH₂O, where R is a C₁-C₁₀ alkyl, 2≦m≦4.2, 0≦n≦0.7, andcharacterized by the specified X-ray diffraction spectrum.

According to another method, the adducts of the invention are preparedby contacting MgCl₂ and alcohol in the absence of the inert liquiddispersant, heating the system at the melting temperature ofMgCl₂-alcohol adduct or above, and maintaining said conditions so as toobtain a completely melted adduct. Said molten adduct is then emulsifiedin a liquid medium which is immiscible with and chemically inert to itand finally quenched by contacting the adduct with an inert coolingliquid thereby obtaining the solidification of the adduct. Inparticular, the adduct is preferably kept at a temperature equal to orhigher than its melting temperature, under stirring conditions, for atime period equal to or greater than 10 hours, preferably from 10 to 150hours, more preferably from 20 to 100 hours. Alternatively, in order toobtain the solidification of the adduct, a spray-cooling process of themolten adduct can be carried out.

The catalyst components obtained from the adducts obtained with theabove described processes show still more improved properties over thecatalyst components prepared by the adducts which have been obtainedwith the same preparation method but without having been maintained forthe requested period of time under the described conditions.

A further method for preparing MgCl₂.pROH.qH₂O adducts, where R is aC₁-C₁₀ alkyl, 2≦p≦6, 0≦q≦1, comprises reacting the MgCl₂ solid particlesand vaporized alcohol in a loop reactor comprising a densified zone inwhich the particles flow in a densified form under the action of gravityand a fast fluidization zone where the particles flow under fastfluidization conditions. As it is known, the state of fast fluidizationis obtained when the velocity of the fluidizing gas is higher than thetransport velocity, and it is characterized in that the pressuregradient along the direction of transport is a monotonic function of thequantity of injected solid, for equal flow rate and density of thefluidizing gas. The terms transport velocity and fast fluidization stateare well known in the art; for a definition thereof, see, for example,“D. Geldart, Gas Fluidization Technology, page 155 et seqq., J.Wiley &Sons Ltd., 1986”. In the second polymerization zone, where the particlesflows in a densified form under the action of gravity, high values ofdensity of the solid are reached (density of the solid=kg of solidparticles per m³ of reactor occupied), which approach the bulk densityof the adduct; a positive gain in pressure can thus be obtained alongthe direction of flow, so that it becomes possible to reintroduce thesolid particles into the fast fluidization zone without the help ofspecial mechanical means. In this way, a “loop” circulation is set up,which is defined by the balance of pressures between the two zones ofthe reactor.

In particular, the above method is suitable to prepare MgCl₂.mROH.nH₂Oadducts, where R is a C₁-C₁₀ alkyl, 2≦m≦4.2, and 0≦n≦0.7, characterizedby the specified X-ray diffraction spectrum, carrying out the reactionbetween MgCl₂ particles and vaporized alcohol in the loop reactor, underconditions such that the vapour pressure of the formed adduct is kept atvalues lower than 30 mmHg when operating at atmospheric pressure.Preferably, the vapour pressure of the adduct is kept at values lowerthan 25 mmHg and more preferably in the range 10-20 mmHg.

Preferably, the reaction between magnesium dichloride and alcohol iscarried out in a loop reactor in which the fast fluidization is obtainedby a flow of an inert gas, such as nitrogen. The particles of the formedadduct are preferably discharged from the densified zone. As mentionedabove, the reaction between magnesium dichloride and alcohol must becarried out under conditions which allow a substantial control of thereaction in order to avoid problems such as melting of the adduct or itssubstantial dealcoholation. Therefore, the temperature within thereactor, and particularly in the zone where the vaporized alcohol isfed, must be carefully controlled so as to maintain the vapour pressureof the adduct within the above limits. In particular, the control of thetemperature is very important in view of the fact that the reaction isgreatly exothermic. Therefore, it is preferred working under conditionssuch that heat exchange is maximized. For the same reason, the feedingof the alcohol has to be controlled in order to obtain an efficientdispersion of the alcohol in the reactor, thus avoiding the formation ofthe so called hot spots. The feeding of the alcohol can be carried outfor example with injection nozzles, preferably located in the fastfluidization zone of the loop reactor. According to an alternativemethod, the alcohol can be fed to the loop reactor in a zone after thedensified zone and before the fast fluidization zone, where acentrifugal mixer (of the Loedige type) is installed in order to directthe solid particles towards the walls of the reactor and create acavitated zone where the alcohol is preferably fed. Preferably, thereactor temperature in correspondence to the alcohol feeding zone shouldbe maintained at values in the range 40-50° C. when operating atatmospheric pressure.

The particles of the adduct discharged from the loop reactor can be thensubjected to a treatment capable of imparting them a sphericalmorphology. In particular, the treatment comprises subjecting theadducts to a temperature equal to or higher than the melting temperatureof the adduct until the adduct is completely melted, said treatmentbeing carried out in absence or presence of an inert liquid dispersant,then emulsifying the molten adduct in a liquid medium which isimmiscible with and chemically inert to it and finally quenching themolten adduct with an inert cooling liquid thereby obtaining thesolidification of the adduct in spherical form. Alternatively, in orderto obtain the solidification of the adduct in spherical form, the moltenadduct can be subjected to a spray-cooling process according to knowntechniques.

The treatment which comprises melting the adduct in the presence of aninert dispersant agent, such as vaseline oil, then emulsifying andfinally quenching said molten adduct, is particularly preferred.

The liquid in which the molten adduct is emulsified is preferably ahydrocarbon liquid such as vaseline oil. The liquid used to quench theemulsion can be equal to or different from the liquid in which themolten adduct is emulsified. Preferably, it is an aliphatic hydrocarbonand more preferably a light aliphatic hydrocarbon such as pentane,hexane, heptane and the like.

The solid adducts having a spherical morphology are very suitable in thepreparation of spherical catalyst components for the polymerization ofolefins and in particular for the gas-phase polymerization process.

The catalyst components to be used in the polymerization of olefinscomprise a transition metal compound of one of the groups IV to VI ofthe Periodic Table of Elements, supported on the adducts of theinvention.

A method suitable for the preparation of said catalyst components,comprises the reaction between the adducts of the invention and thetransition metal compound. Among transition metal compounds particularlypreferred are titanium compounds of formula Ti(OR)_(n)X_(y-n) in which nis comprised between 0 and y; y is the valency of titanium; X is halogenand R is an alkyl radical having 1-8 carbon atoms or a COR group. Amongthem, particularly preferred are titanium compounds having at least oneTi-halogen bond such as titanium tetrahalides or halogenalcoholates.Preferred specific titanium compounds are TiCl₃/TiCl₄, Ti(OBu)₄,Ti(OBu)Cl₃, Ti(OBu)₂Cl₂, Ti(OBu)₃Cl. Preferably the reaction is carriedout by suspending the adduct in cold TiCl₄ (generally 0° C.); then theso obtained mixture is heated up to 80-130° C. and kept at thistemperature for 0.5-2 hours. After that the excess of TiCl₄ is removedand the solid component is recovered. The treatment with TiCl₄ can becarried out one or more times.

The reaction between transition metal compound and the adduct can alsobe carried out in the presence of an electron donor compound (internaldonor) in particular when the preparation of a stereospecific catalystfor the polymerization of olefins is to be prepared. Said electron donorcompound can be selected from esters, ethers, amines, silanes andketones. In particular, the alkyl and aryl esters of mono orpolycarboxylic acids such as for example esters of benzoic, phthalic andmalonic acid, are preferred. Specific examples of such esters aren-butylphthalate, di-isobutylphthalate, di-n-octylphthalate,ethyl-benzoate and p-ethoxy ethyl-benzoate. Moreover, can beadvantageously used also the 1,3 diethers of the formula:

wherein R^(I), R^(II), R^(III), R^(IV), R^(V) and R^(VI) equal ordifferent to each other, are hydrogen or hydrocarbon radicals havingfrom 1 to 18 carbon atoms, and R^(VII) and R^(VIII), equal or differentfrom each other, have the same meaning of R^(I)-R^(VI) except that theycannot be hydrogen; one or more of the R^(I)-R^(VIII) groups can belinked to form a cycle. The 1,3-diethers in which R^(VII) and R^(VIII)are selected from C₁-C₄ alkyl radicals are particularly preferred.

The electron donor compound is generally present in molar ratio withrespect to the magnesium comprised between 1:4 and 1:20.

Preferably, the particles of the solid catalyst components havesubstantially spherical morphology and an average diameter comprisedbetween 5 and 150 μm. The term substantial spherical morphology meansthose particles having a ratio between the greater and smaller axisequal to or lower than 1.5 and preferably lower than 1.3.

Before the reaction with the transition metal compound, the adducts ofthe present invention can also be subjected to a dealcoholationtreatment aimed at lowering the alcohol content and increasing theporosity of the adduct itself. The dealcoholation can be carried outaccording to known methodologies such as those described in EP-A-395083.Depending on the extent of the dealcoholation treatment, partiallydealcoholated adducts can be obtained having an alcohol contentgenerally ranging from 0.1 to 2.6 moles of alcohol per mole of MgCl₂.After the dealcoholation treatment the adducts are reacted with thetransition metal compound, according to the techniques described above,in order to obtain the solid catalyst components.

The solid catalyst components according to the present invention show asurface area (by B.E.T. method) generally between 10 and 500 m²/g andpreferably between 20 and 350 m²/g, and a total porosity (by B.E.T.method) higher than 0.15 cm³/g preferably between 0.2. and 0.6 cm³/g.

Surprisingly, the catalyst components comprising the reaction product ofa transition metal compound with a MgCl₂-alcohol adduct which is in turnobtained by partially dealcoholating the adducts of the invention, showimproved properties, particularly in terms of activity, with respect tothe catalyst components prepared from the dealcoholated adducts of theprior art.

The catalyst components of the invention form catalysts for thepolymerization of alpha-olefins CH₂═CHR, wherein R is hydrogen or ahydrocarbon radical having 1-12 carbon atoms, by reaction with Al-alkylcompounds. The alkyl-Al compound is preferably chosen among the trialkylaluminum compounds such as for example triethylaluminum,triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum,tri-n-octylaluminum. It is also possible to use alkylaluminum halides,alkylaluminum hydrides or alkylaluminum sesquichlorides such as AlEt₂Cland Al₂Et₃Cl₃ optionally in mixture with said trialkyl aluminumcompounds.

The Al/Ti ratio is higher than 1 and is generally comprised between 20and 800.

In the case of the stereoregular polymerization of α-olefins such as forexample propylene and 1-butene, an electron donor compound (externaldonor) which can be the same or different from the compound used asinternal donor can be used in the preparation of the catalysts disclosedabove. In case the internal donor is an ester of a polycarboxylic acid,in particular a phthalate, the external donor is preferably selectedfrom the silane compounds containing at least a Si—OR link, having theformula R_(a) ¹R_(b) ²Si(OR³)_(c), where a and b are integer from 0 to2, c is an integer from 1 to 3 and the sum (a+b+c) is 4; R¹, R², and R³,are alkyl, cycloalkyl or aryl radicals with 1-18 carbon atoms.Particularly preferred are the silicon compounds in which a is 1, b is1, c is 2, at least one of R¹ and R² is selected from branched alkyl,cycloalkyl or aryl groups with 3-10 carbon atoms and R³ is a C₁-C₁₀alkyl group, in particular methyl. Examples of such preferred siliconcompounds are methylcyclohexyldimethoxysilane, diphenyldimethoxysilane,methyl-t-butyldimethoxysilane, dicyclopentyldimethoxysilane. Moreover,are also preferred the silicon compounds in which a is 0, c is 3, R² isa branched alkyl or cycloalkyl group and R₃ is methyl. Examples of suchpreferred silicon compounds are cyclohexyltrimethoxysilane,t-butyltrimethoxysilane and thexyltrimethoxysilane.

Also the 1,3 diethers having the previously described formula can beused as external donor. However, in the case 1,3-diethers are used asinternal donors, the use of an external donor can be avoided, as thestereospecificity of the catalyst is already sufficiently high.

As previously indicated the components of the invention and catalystsobtained therefrom find applications in the processes for the(co)polymerization of olefins of formula-CH₂═CHR in which R is hydrogenor a hydrocarbon radical having 1-12 carbon atoms.

The catalysts of the invention can be used in any of the olefinpolymerization processes known in the art. They can be used for examplein slurry polymerization using as diluent an inert hydrocarbon solvent,or bulk polymerization using the liquid monomer (for example propylene)as a reaction medium. Moreover, they can also be used in thepolymerization process carried out in gas-phase operating in one or morefluidized or mechanically agitated bed reactors.

The polymerization is generally carried out at temperature of from 20 to120° C, preferably of from 40 to 80° C. When the polymerization iscarried out in gas-phase the operating pressure is generally between 0.1and 10 MPa, preferably between 1 and 5 MPa. In the bulk polymerizationthe operating pressure is generally between 1 and 6 MPa preferablybetween 1.5 and 4 MPa.

The catalysts of the invention are very useful for preparing a broadrange of polyolefin products. Specific examples of the olefinic polymerswhich can be prepared are: high density ethylene polymers (HDPE, havinga density higher than 0.940 g/cc), comprising ethylene homopolymers andcopolymers of ethylene with alpha-olefins having 3-12 carbon atoms;linear low density polyethylenes (LLDPE, having a density lower than0.940 g/cc) and very low density and ultra low density (VLDPE and ULDPE,having a density lower than 0.920 g/cc, to 0.880 g/cc) consisting ofcopolymers of ethylene with one or more alpha-olefins having from 3 to12 carbon atoms, having a mole content of units derived from theethylene higher than 80%; isotactic polypropylenes and crystallinecopolymers of propylene and ethylene and/or other alpha-olefins having acontent of units derived from propylene higher than 85% by weight;copolymers of propylene and 1-butene having a content of units derivedfrom 1-butene comprised between 1 and 40% by weight; heterophasiccopolymers comprising a crystalline polypropylene matrix and anamorphous phase comprising copolymers of propylene with ethylene and orother alpha-olefins.

The following examples are given to illustrate and not to limit theinvention itself.

Characterization

The properties reported below have been determined according to thefollowing methods:

X-ray diffraction spectra were carried out with a Philips PW 1710instrument using the CuK_(α)(λ=1,5418) with a 40 Kv tension generator, a20 mA current generator and a receiving slit of 0.2 mm. The X-raydiffraction patterns were recorded in the range between 2θ=5° and 2θ=15°with a scanning rate of 0.05° 2θ/10 sec. The instrument was calibratedusing the ASTM 27-1402 standard for Silicon. The samples to be analyzedwere closed in a polyethylene bag of 50 μm thickness operating in adry-box.

The DSC measurement were carried out with a METTLER DSC 30 instrument ata scanning rate of 5° C./min in the range 5-125° C. Aluminum capsuleshaving a volume of 40 μl filled with the samples in a dry-box were usedin order to avoid hydration of the samples.

The viscosity measurement were carried out according to ASTM D445-65using a Cannon-Fenske type viscosimeter. During the measurement thesamples are maintained in a dry nitrogen environment in order to avoidhydration.

EXAMPLES

General Procedure for the Preparation of the Catalyst Component

Into a 11 steel reactor provided with stirrer, 800 cm³ of TiCl₄ at 0° C.were introduced; at room temperature and whilst stirring 16 g of theadduct were introduced together with an amount of diisobutylphthalate asinternal donor so as to give a donor/Mg molar ratio of 10. The whole washeated to 100° C. over 90 minutes and these conditions were maintainedover 120 minutes. The stirring was stopped and after 30 minutes theliquid phase was separated from the sedimented solid maintaining thetemperature at 100° C. A further treatment of the solid was carried outadding 750 cm³ of TiCl₄ and heating the mixture at 120° C. over 10 min.and maintaining said conditions for 60 min under stirring conditions(500 rpm). The stirring was then discontinued and after 30 minutes theliquid phase was separated from the sedimented solid maintaining thetemperature at 120° C. Thereafter, 3 washings with 500 cm³ of anhydroushexane at 60° C. and 3 washings with 500 cm³ of-anhydrous hexane at roomtemperature were carried out. The solid catalyst component obtained wasthen dried under vacuum in nitrogen environment at a temperature rangingfrom 40-45° C.

General Procedure for the Polymerization Test

A 4 liter steel autoclave equipped with a stirrer, pressure gauge,thermometer, catalyst feeding system, monomer feeding lines andthermostatting jacket, was used. The reactor was charged with 0.01 gr ofsolid catalyst component 0,76 g of TEAL, 0.076 g of dicyclopentyldimetoxy silane, 3.2 l of propylene, and 1.5 l of hydrogen. The systemwas heated to 70° C. over 10 min. under stirring, and maintained underthese conditions for 120 min. At the end of the polymerization, thepolymer was recovered by removing any unreacted monomers and was driedunder vacuum.

Example 1

Preparation of the Adduct

100 gr of MgCl₂ were dispersed in 1200 cm³ of OB55 vaselin oil into avessel reactor. The temperature was raised up to 160° C. and 135,2 g. ofvaporized EtOH having the same temperature were slowly added to themixture. At the end of the addition, the mixture was cooled up to 125°C. and maintained at this temperature obtaining a completely melted andclear adduct.

This mixture was kept at 125° under stirring conditions by means of aUltra Turrax T-45 type stirrer operating at 2000 rpm. Thereupon themixture was discharged into a vessel containing hexane which was keptunder stirring and cooled so that the final temperature did not exceed12° C. The solid particles of the MgCl₂.EtOH adduct recovered,containing 57% by weight of EtOH, were then washed with hexane and driedat 40° C. under vacuum.

The X-ray spectrum of the adduct showed in the range of 2θ diffractionangles between 5° and 15° three diffraction lines present at diffractionangles 2θ of 8.80° (100), 9.40° (63) and 9.75° (54); the number inbrackets represents the intensity I/I_(o) with respect to the mostintense line.

The DSC profile showed a peak at 100.5° C. and a peak at 81.4° C. for atotal fusion enthalpy of 107.9 J/g. The fusion enthalpy associated withthe peak at 81.4° C. was 6.9 J/g corresponding to 6.3% of the totalfusion enthalpy. The catalyst component, prepared according to thegeneral procedure, was tested according to the general polymerizationprocedure described above and gave the results reported in Table 1.

Example 2

100 gr of MgCl₂ were introduced in a vessel reactor which contained135.2 g of EtOH at room temperature and under stirring. Once theaddition of MgCl₂ was completed the temperature was raised up to 125° C.and kept at this value for 10 hours.

The so obtained adduct was transferred in a vessel containing 1200 cm³of OB55 vaseline oil, and kept at 125° C. under stirring conditions bymeans of a Ultra Turrax T-45 type stirrer operating at 2000 rpm for atotal time of 20 hours. Thereupon the mixture was discharged into avessel containing hexane which was kept under stirring and cooled sothat the final temperature did not exceed 12° C. The solid particles ofthe MgCl₂.EtOH adduct recovered, containing 57% by weight of EtOH, werethen washed with hexane and dried at 40° C. under vacuum.

The X-ray spectrum of the adduct showed in the range of 2θ diffractionangles between 5° and 15° three diffraction lines present at diffractionangles 2θ of 8.83° (100), 9.42° (65) and 9.80° (74); the number inbrackets represents the intensity I/I_(o) with respect to the mostintense line. The DSC profile showed a peak at 103.4° C., a peak at97.2° C., a peak at 80.1° C. and a peak at 70.2° C. for a total fusionenthalpy of 101 J/g. The fusion enthalpy associated with the peaks at80.1° C. and at 70.2° C. was 16.5 J/₉ corresponding to 16.3% of thetotal fusion enthalpy.

The catalyst component, prepared according to the general procedure, wastested according to the general polymerization procedure described aboveand gave the results reported in Table 1.

Example 3

100 gr of MgCl₂ were introduced in a vessel reactor which contained135.2 g of EtOH at room temperature and under stirring. Once theaddition of MgCl₂ was completed the temperature was raised up to 125° C.and the system maintained at this temperature and under stirringconditions for 70 hours. The so obtained adduct was transferred in avessel containing 1200 cm³ of OB55 vaseline oil, and kept at 125° C.under stirring conditions by means of a Ultra Turrax T-45 type stirreroperating at 2000 rpm. Thereupon the mixture was discharged into avessel containing hexane which was kept under stirring and cooled sothat the final temperature did not exceed 12° C. The solid particles ofthe MgCl₂.EtOH adduct recovered, containing 57.4% by weight of EtOH,were then washed with hexane and dried at 40° C. under vacuum.

The X-ray spectrum of the adduct showed in the range of 2θ diffractionangles between 5° and 15° three diffraction lines present at diffractionangles 2θ of 8.83° (100), 9.42° (64) and 9,82° (73); the number inparentheses represents the intensity I/I_(o) with respect to the mostintense line.

The DSC profile showed a peak at 105.7° C., and a peak at 64.6° C. for atotal fusion enthalpy of 90.3 J/g. The fusion enthalpy associated withthe peak at 64.6° was of 0.7 J/g corresponding to 0.77% of the totalfusion enthalpy.

The catalyst component, prepared according to the general procedure, wastested according to the general polymerization procedure described aboveand gave the results reported in Table 1.

Example 4

In a loop reactor comprising a fast fluidization zone and a densifiedzone when the particles flow under the action of gravity were charged100 g of MgCl₂. Then, 135.2 g of EtOH vaporized in a oven at 180° C.,were conveyed, by a dry nitrogen flow, to the cavitated zone of aLoedige type apparatus placed into the loop reactor after the densifiedzone and before the fast fluidization zone. The feeding of EtOH wascontrolled so as to maintain the temperature in the feeding zone in therange between 42 to 48° C. Once the feeding of the alcohol was completedthe particles of the adduct were transferred in a vessel containing 1200cm³ of OB55 vaseline oil, the temperature was raised up to 125° C. andthe system maintained under said conditions until the adduct becamecompletely melted and clear. This mixture was kept at 125° C. understirring conditions by means of a Ultra Turrax T-45 type stirreroperating at 2000 rpm. Thereupon the mixture was discharged into avessel containing hexane which was kept under stirring and cooled sothat the final temperature did not exceed 12° C.

The solid particles of the MgCl₂.EtOH adduct recovered, containing 56.5%by weight of EtOH were then washed with hexane and dried at 40° C. undervacuum.

The X-ray spectrum of the adduct showed in the range of 2θ diffractionangles between 5° and 15° three diffraction lines present at diffractionangles 2θ of 8.90° (100), 9.48° (75) and 9.84° (63); the number inparentheses represents the intensity I/I_(o) with respect to the mostintense line.

The DSC profile showed a peak at 108.2° C., and a peak at 69.1° C. for atotal fusion enthalpy of 97.7 J/g. The fusion enthalpy associated withthe peak at 69.1° C. was of 3.1 J/g corresponding to 3.1% of the totalfusion enthalpy.

The catalyst component, prepared according to the general procedure, wastested according to the general polymerization procedure described aboveand gave the results reported in Table 1.

Comparison Example 5

100 gr of MgCl₂ were dispersed in 1200 cm³ of OB55 vaselin oil into avessel reactor and 135,2 g of liquid EtOH were added to the mixture. Atthe end of the addition the temperature was raised up to 125° C. andkept at this temperature for 2 hours. The mixture was kept at 125° C.under stirring conditions by means of a Ultra Turrax T-45 type stirreroperating at 2000 rpm. Thereupon the mixture was discharged into avessel containing hexane which was kept under stirring and cooled sothat the final temperature did not exceed 12° C. The solid particles ofthe MgCl₂-EtOH adduct containing 57% by weight of EtOH were then washedwith hexane and dried at 40° C. under vacuum.

The X-ray spectrum of the adduct showed in the range of 2θ diffractionangles between 5° and 15° four diffraction lines present at diffractionangles 2θ of 8.84° (79.3), 9.2° (100), 9.43° (68.2) and 9.82° (19.5);the number in parentheses represents the intensity I/I_(o) with respectto the most intense line. The DSC profile showed a peak at 99.8° C., apeak at 82.8° C., and a peak at 71.3° C. for a total fusion enthalpy of107.2 J/g. The fusion enthalpy associated with the peak at 82.8° C. andthe peak at 71.3° C. was of 57.1 J/g corresponding to 53.2% of the totalfusion enthalpy. The catalyst component, prepared according to thegeneral procedure, was tested according to the general polymerizationprocedure described above and gave the results reported in Table 1.

Example 6

An MgCl₂-EtOH adduct prepared according to the procedure of Example 2was thermally dealcoholated until the content of EtOH reached 44% b.w.Then, the partially dealcoholated adduct was used to prepare, accordingto the general procedure, the catalyst component which was then used ina polymerization test carried out according to the procedure describedabove. The results are reported in Table 1.

Comparison Example 7

An MgCl₂-EtOH adduct prepared according to the procedure of ComparisonExample 5 was thermally dealcoholated until the content of EtOH reached44% b.w. Then, the partially dealcoholated adduct was used to prepare,according to the general procedure, the catalyst component which wasthen used in a polymerization test carried out according to theprocedure described above. The results are reported in Table 1.

Example 8

83 gr of MgCl₂ were introduced in a vessel reactor which contained 170 gof EtOH at −19° C. and under stirring conditions. Once the addition ofMgCl₂ was completed the temperature was raised up to 100° C. and kept atthis value for 5 hours.

The so obtained adduct was transferred in a vessel containing 1200 cm³of OBS5 vaseline oil, and kept at 125° C. under stirring conditions bymeans of a Ultra Turrax T-45 type stirrer operating at 2000 rpm for atotal time of 10 hours. Thereupon the mixture was discharged into avessel containing hexane which was kept under stirring and cooled sothat the final temperature did not exceed 12° C. The solid particles ofthe MgCl₂.EtOH adduct recovered, containing 64% by weight of EtOH, werethen washed with hexane and dried at 40° C. under vacuum. The DSCprofile showed a peak at 100.7° C., and a peak at 56.5° C. for a totalfusion enthalpy of 103 J/g. The fusion enthalpy associated with the peakat 56.5° C. was 12.8 J/g corresponding to 12.4% of the total fusionenthalpy. The catalyst component, prepared according to the generalprocedure, was tested according to the general polymerization proceduredescribed above and gave the results reported in Table 1.

TABLE 1 Poured bulk Example Activity density Morphological evaluation 170 0.43 spherical polymer 2 70 0.43 spherical polymer 3 80 0.45spherical polymer 4 70 0.43 spherical polymer comp. 5 50 0.40 sphericalpolymer with breakages 6 40 0.43 spherical polymer comp. 7 35 0.4spherical polymer 8 60 0.4 spherical polymer

What is claimed is:
 1. Process for the preparation of MgCl₂.pROH.qH₂Oadducts, where R is a C₁-C₁₀ alkyl, 1≦p≦6, and, o≦q≦1 which comprisesreacting MgCl₂ solid particles and vaporized alcohol and, optionally,water, in a loop reactor comprising a densified zone in which theparticles flow in a densified form under the action of gravity and afast fluidization zone where the particles flow under fast fluidization.2. Process according to claim 1 in which the fluidization is obtained byflow of an inert gas, and in which particles of magnesiumdichloride-alcohol adduct are discharged from the densified zone. 3.Process according to claim 2, in which the alcohol is fed into the loopreactor with injection nozzles located in the fast fluidization zone. 4.Process according to claim 2 in which the alcohol is fed into the loopreactor in a zone after the densified zone and before the fastfluidization zone.
 5. Process according to claim 4 in which the alcoholis fed into a cavitated zone created by a centrifugal mixer located inthe loop reactor in a zone after the densified zone and before the fastfluidization zone.
 6. The process according to claim 5, wherein thecentrifugal mixer is a horizontal mixer.
 7. The process according toclaim 2, wherein the inert gas is nitrogen.
 8. Process according toclaim 1 in which 2≦p≦4.2 and 0≦q≦0.7, said process being carried outsuch that the vapor pressure of the adduct is lower than 30 mmHg whenmeasured at atmospheric pressure.
 9. Process according to claim 8 inwhich the vapor pressure of the adduct is lower than 25 mmHg. 10.Process according to claim 9 in which the alcohol is fed into thereactor in an alcohol feeding zone and the temperature within thereactor in the alcohol feeding zone is in the range of from 40° to 50°C.
 11. Process according to claim 9 in which the vapor pressure of theadduct is in the range of 10-20 mmHg.
 12. Process according to claim 1,further comprising: heating the particles of the adduct discharged fromthe loop reactor at a temperature equal to or higher than the meltingtemperature of the adduct and maintaining the temperature at values suchthat the adduct it completely melted; emulsifying the molten adduct in aliquid medium which is immiscible with and chemically inert to saidadduct; quenching the emulsion by contracting the adduct with an inertcooling liquid thereby obtaining the solidified adduct.
 13. Processaccording to claim 1, further comprising: heating the particles of theadduct discharged from the loop reactor at a temperature equal to orhigher than the melting temperature of the adduct and maintaining thetemperature at values such that the adduct is completely melted; spraycooling the molten adduct thereby obtaining the solidified adduct. 14.Process for the preparation of an adduct MgCl₂.mROH.nH₂O, where R is aC₁-C₁₀ alkyl, 2 ≦m≦4.2 and 0≦n≦0.7, wherein the adduct has an X-raydiffraction spectrum in which in the range of 2θ diffraction anglesbetween 5° and 15°, three diffraction lines are present at diffractionangles of 8.8°±0.2°, 9.4°±0.2, and 9.8°±0.2, the most intensediffraction line being the one at 8.8°±0.2°, the intensity of the othertwo diffraction lines being at least 0.2 times the intensity of the mostintense diffraction line, the process comprising: (a) forming a mixtureby contacting MgCl₂ and alcohol and, optionally, water, in thesubstantial absence of an inert liquid dispersent; (b) heating themixture to a temperature equal to or higher than the melting point ofthe adduct to form a molten adduct; (c) emulsifying the molten adduct ina liquid medium which is immiscible with and chemically inert to theadduct; (d) quenching the emulsion by contacting the adduct with aninert cooling liquid.
 15. The process according to claim 14, wherein, instep b, the adduct is kept at a temperature equal to or higher than itsmelting point, under stirring conditions, for more than 10 hours. 16.The process according to claim 15, wherein in step (b), the adduct iskept at a temperature equal to or higher than its melting point, understirring conditions, for more than 10 hours and no more than 150 hours.17. Process for the preparation of an adduct MgCl₂.mROH.nH₂O, where R isa C₁-C₁₀ alkyl, 2≦m≦4.2 and 0≦n≦0.7, wherein the adduct has an X-raydiffraction spectrum in which in the range of 2θ diffraction anglesbetween 5° and 15°,three diffraction lines are present at diffractionangles of 8.8°±0.2°, 9.4°±0.2, and 9.8°±0.2, the most intensediffraction line being the one at 8.8°±0.2°, the intensity of the othertwo diffraction lines being at least 0.2 times the intensity of the mostintense diffraction line, the process comprising: (a) forming a mixtureby contacting MgCl₂ and alcohol and, optionally, water, in thesubstantial absence of an inert liquid dispersent; (b) heating thesystem to a temperature equal to or higher than the melting point of theadduct to form a molten adduct; (c) spray cooling the molten adduct. 18.The process according to claim 17, wherein, in step (b), the adduct iskept a temperature equal to or higher than its melting point, understirring conditions, for more than 10 hours.
 19. The process accordingto claim 18, wherein in step (b), the adduct is kept at a temperatureequal to or higher than its melting point, under stirring conditions,for more than 10 hours and no more than 150 hours.